mpowell1991 :
Sapphire Thunder :
For 500$ you may have to look a bit 2nd hand (used) parts to get a truly good build.
What are your current full specs?
Would a BioStar TA970 with Fx-6300 for $110 be a good start?
The BioStar is low grade motherboard so normally wouldn't get it, but it's a good enough starting point.
You can just later upgrade the motherboard.
If you have already DDR3 in your pc, you can re-use that and possibly just add more.
So that leaves you bunch of money for good gpu and possibly new power supply.
GTX 960 4gb should do the trick. (around 250$)
Also CoolerMaster Hyper 212 EVO as cooler for around 30$